Months of angry debate between Northern Virginia officials and the Metropolitan Washington Airports Authority are slated to end this week as leaders decide on the fate and the cost of Metrorail to Washington Dulles International Airport and into Loudoun County. Observers who have long fought for rail to Dulles are optimistic that the project will move forward at a cost of about $2.8 billion, to be paid largely by Fairfax and Loudoun County taxpayers, and drivers along the Dulles Toll Road. That price tag is down nearly $1 billion from previous estimates, and includes an aboveground instead of an underground station at the airport.

But the lower-cost outcome relies on agreement among the two counties and the airports authority about a funding proposal that requires significant sacrifices from all three. Acceptance of that proposal, put forth earlier this month by U.S. Secretary of Transportation Ray LaHood, is far from guaranteed.